body {
  width: 100%;
  height: 100%;
}
.side_menu,
a {
  font-size: 25px;
  line-height: 40px;
}
.side_menu {
  height: 80%;
  width: 70px;
  margin: 50px 0;
  background-color: #252c35;
  position: absolute;
  left: 0;
  text-align: left;
  opacity: 0.7;
  align-items: center;
  text-align: center;
}
.top_menu,
a {
  font-family: 宋体;
}
.footer {
  position: absolute;
  bottom: 0;
  width: 100%;
  /* Set the fixed height of the footer here */
  background-color: #2f4056;
}
.icon_side {
  width: 60px;
  height: 60px;
  margin: 10px 0;
  padding: 1px 0;
}
.arrow-custom-down {
  margin: 5px;
  width: 0;
  height: 0;
  border-top: 13px solid white;
  border-left: 14px solid transparent;
  border-right: 14px solid transparent;
}
.arrow-custom-down:hover {
  display: inline-block;
  border-bottom: 3px solid orange;
  border-left: 14px solid transparent;
  border-right: 14px solid transparent;
  cursor: pointer;
}

.divrun {
  position: absolute;
  width: 60%;
  height: 60%;
  background: white;
  border-radius: 25px;
}

.icon_side:hover {
  background-color: white;
  opacity: 0.7;
}

img:hover {
  opacity: 0.8;
}

.close_button {
  float: right;
  width: 25px;
  height: 25px;
  margin: 5px;
}
.little_button {
  float: right;
  width: 25px;
  height: 25px;
  margin: 5px;
}
.big_button {
  float: right;
  width: 25px;
  height: 25px;
  margin: 5px;
}
.close_button:hover {
  background-color: red;
  border-radius: 25px;
}
.little_button:hover {
  background-color: white;
  border-radius: 25px;
  opacity: 0.1;
}
.big_button:hover {
  background-color: white;
  border-radius: 25px;
  opacity: 0.1;
}
.cmd {
  width: 100%;
  height: 100%;
  background-color: #000000;
}
.cmddiv {
  width: 100%;
}
#cmdtext {
  border: 1px;
  height: 4%;
  width: 70%;
  padding-left: 5px;
  font-size: 25px;
  background-color: #000000;
  color: whitesmoke;
  border: none;
}
.desktop {
  float: right;
  margin: 10px;
}
.folder:hover {
  background-color: white;
  opacity: 0.7;
}

* {
  user-select: none;
}
.folderdiv {
  padding: 5px;
}
.folderdiv:hover {
  opacity: 0.8;
  background-color: rgba(255, 255, 255, 0.4);
}
.folderdivicon {
  margin-left: 5px;
  width: 30px;
  height: 30px;
}
ul {
  list-style: none;
}
a {
  text-decoration: none;
  color: #333;
}
.contextmenu {
  width: 200px;
  border-radius: 10%;
  padding: 20px;
  background-color: #2b2b2b;
  position: absolute;
  top: 10px;
  left: 10px;
  display: none;
  z-index: 9999999;
}
.contextmenu li {
  height: 40px;
  line-height: 40px;
}
.contextmenu li a {
  color: white;
  opacity: 0.9;
  display: block;
  padding: 0 30px;
}
.contextmenu li a:hover {
  background-color: rgba(255, 255, 255, 0.4);
}
.folderstudy {
  width: 50px;
  height: 50px;
  text-align: center;
  font-size: 10px;
  margin: 15px;
  display: inline-block;
}
.studybook {
  color: white;
  user-select: none;
  display: -webkit-box;
  -webkit-box-orient: vertical;
  -webkit-line-clamp: 2;
  overflow: hidden;
}
.tools {
  border-radius: 10px;
  display: none;
  background-color: #2b2b2b;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
  padding: 12px 16px;
  float: right;
}
